I've been trying to get oauth working with the dropbox api, and I kept running into SSLException issues. The dropbox API only works across https, and it seems that oauth using an older version of httpclient. The solution is to add the following in the build config:
build 'org.apache.httpcomponents:httpcore:4.0.1', 'org.apache.httpcomponents:httpclient:4.0.1'
It may help other users experiencing problems with SSL Exceptions